Field sprayers have become increasingly larger with a wide spray area as production areas, and farming has become more capital-intensive. Liquid sprayers are used for applying pesticides, herbicides and fertilizers. The timing of such applications is critical at certain periods of the year.
One of the problems encountered in spraying is that on the prairies or other wide-open areas, there is constant wind which may blow for as long as a week or two at a time, thereby preventing the farmer from carrying out an effective spraying program when and where he wants to.
In order to alleviate this problem, various devices have been developed to reduce drift of the spray caused by the wind. The basic concept has been to provide a shroud or cover over the spray boom to prevent the wind from entering the area being sprayed. Such a structure may comprise a drape, a snow fence type structure, or skirt. Such a device is disclosed and claimed in Canadian Patent 1,206,126 (McCrea).
Others have tried such things as an inflatable bag structure, such as that shown in Canadian Patent 1,094,517 (Jones).
Another type of device employs a type of air foil whereby the wind moves along over the skirt-like structure forcing it downwardly such as that shown in Canadian Patent 1,225,374 (Rogers).
Still others have attempted to protect the spray by means of an inverted cone around each of the nozzles, such as the Brandt "Wind Cone".
All of the above devices reduce drift to a certain extent, but generally at the expense of distribution. Furthermore, another serious problem with such devices is that spray nozzles and spray patterns are concealed from the operator by the shield making it difficult for the operator to tell if all the nozzles are operating properly. As well, many of these structures are extremely expensive to make and cumbersome to assemble, maintain, and clean.
The present invention seeks to solve the spray drift problem by employing an entirely new principle. Rather than blocking out the wind and reducing drift at the expense of distribution, the present invention employs the wind to the advantage of the sprayer.
It is an object of the present invention to provide a spray shield that is inexpensive to make, easy to assemble, and which fits most sprayers which employ wet spray booms which are transverse to the direction of travel in the field position.
It is a further object of the present invention to reduce drift and improve distribution of spray.
Finally, it is an object of the present invention to provide a spray shield which will not clog with chemicals and soil that requires little or no cleaning and maintenance, and still allows the operator to see the spray pattern from the tractor cab.